Mediation Effect of Obesity on the Association of Age at Menarche With Blood Pressure Among Women in Southwest China

Abstract

Background Previous studies have been inconsistent about the association between age at menarche and high blood pressure. Little is known about such association across a wide range of menarcheal ages in less developed ethnic minority regions in China. We aimed to explore the association between age at menarche and high blood pressure (BP; ≥140/90 mm Hg) and to examine the mediating effect of obesity and the moderating effect of menopausal status on this association. Methods and Results A total of 45 868 women from the baseline data of the CMEC (China Multi-Ethnic Cohort) were included in this study. Binary logistic regression was used to analyze the relationship between age at menarche and high BP, and the mediation model was used to evaluate the mediating effects of body mass index and waist circumference on the association of age at menarche with high BP. The mean age at enrollment and age at menarche of participants in our study were 49.3 (SD=10.7) and 14.7 (SD=2.1) years, respectively. Late menarche was associated with a lower risk of high BP (odds ratio, 0.831 [95% CI, 0.728-0.950]). The risk of high BP decreased by 3.1% with each year's delay in the onset of menarche (P for trend <0.001). Body mass index and waist circumference could partially mediate the association of age at menarche and high BP with the indirect effect of body mass index (odds ratio, 0.998 [95% CI, 0.997-0.998]) and waist circumference (odds ratio, 0.999 [95% CI, 0.998-0.999]). In addition, the mediation effects were modified by the status of menopause. Conclusions Women with late menarche have a lower risk of high BP, and obesity could be one of the important mediators. Obesity prevention is an efficient strategy to reduce the association between age at menarche and high BP, especially in premenopausal women.

Keywords: age at menarche; blood pressure; multiethnic southwestern Chinese women; obesity.

Figure 1. A schematic overview of the inclusion and exclusion for the participants.

HDL‐C indicates high‐density lipoprotein cholesterol; LDL‐C, low‐density lipoprotein cholesterol; and WC, waist circumference.

Figure 2. The path diagram of hypothesis model.

BMI indicates body mass index; and WC, waist circumference.

Figure 3. Adjusted odds ratio (ORs) of high BP associated with late age at menarche by several covariates.

In addition to adjustment for marital status, education level, menopausal status, number of live births, ever oral contraceptive use, cholesterol, triglycerides, HDL‐C, and LDL‐C, the covariates of ethnic group, smoking status, alcohol consumption, DASH score, BMI, physical activity, family history of hypertension, and history of diabetes were mutually adjusted in the analysis. Small black squares are ORs, and their horizontal lines indicate the corresponding 95% CIs. The diamond indicates the overall change and its 95% CI. BMI indicates body mass index; DASH, Dietary Approaches to Stop Hypertension; HDL‐C, high‐density lipoprotein cholesterol; LDL‐C, low‐density lipoprotein cholesterol; and OR, odds ratio.

Figure 4. The mediation effect of BMI (left panel) and WC (right panel) on the association of age at menarche with high BP.

BMI indicates body mass index; BP, blood pressure; OR, odds ratio; and WC, waist circumference.